Life Living things are organized around cycles that follow one another: day and night, seasons and on the coast tides are probably the most important. Plants and animals have adapted to live according to these cyclesusing different rhythms, according to their evolutionary adaptations.
There are mainly two types of life cycle among plants: annuals and perennials. Two life cycles that contrast each other and that in some way mark the rhythms of ecosystems. While Annual plants complete their existence in less than a year, perennials endure, defy the passage of time.. These dynamics support complex ecological networks and reflect adaptation to different environments. It is not for nothing that plants are the basis of terrestrial ecosystems.
Perennial and annual plants are found different roles in habitatsand their populations are maintained in the balance necessary for the proper functioning of ecosystems. However, anthropogenic climate change poses new challenges and changes this balance.
The poppy is a classic example of an annual plant — Ilo/pixabay
A complete life cycle in a few months: annual plants
Annual life cycle It is one of the most effective adaptations for species to survive harsh winter conditions. When winter comes, annuals release huge amounts of seeds and then they just die. Seed It is the most resistant plant organ, it can withstand even very strong adverse effects and only needs a little heat and a little moisture. germinate. This usually happens in early spring.
Once it germinates, the annual plant is ahead career in sprint. In a few months it should develop its leaves, its stem, open its flowers, pollinate and ripen its fruitsbefore next autumn comes.
His existence, though short, plays essential role in ecosystems, occupying ecological niches that other plants cannot. An annual plant, for example, needs very little soil to grow; its roots are weak and underdeveloped, just enough to get water and support the plant with light tissues during its short life. Its accelerated life cycle makes this possible respond quickly to environmental opportunitiessuch as short periods of abundant water or temporary clearings in the forest.
They also fit important functions in the ecosystem. Although an annual plant can germinate in a rocky environment and very little soil, at the end of the year this plant dies and its body, decomposed by microorganisms, will support soil formation new and with it initiate the formation of a more complex ecosystem.
Classic examples of annual plants are most grasses, sunflowers, poppies, lettuce, peas or broad beans.
Despite its large size, the sunflower is an annual plant — Leopictures/pixabay
Defy the passage of years: perennial plants
If the annual plant is a runner sprint, a perennial plant is a marathon plant nature. Annual plants are characterized by living longer than two years. More than two because there is a minority type, biennial plant, which will end its life cycle in exactly two years; the first to develop stem, leaves and roots and the second to hatch flowers.
Perennial plants have an extended life cycle allowing them to grow and flourish again and again. They tend to develop thickening on the stem, which is sometimes woody and generate robust roots, able to access deeper sources of water and nutrients. They have too nutrient storage tissues in the roots or stems — sometimes underground, the so-called rhizomes—.
The life cycle of a perennial plant also begins with the germination of a seed, but proceeds at a slower pace, because it requires more demanding conditions. Once a small seedling is formed, the stem and root will begin to grow. Unlike annuals, which seem to be in a hurry to flower, perennials take longer, many do not even bloom in their first year of life. They devote most of their efforts to hoarding nutrients to survive the winter.
Also flowering is much longer than annuals. Furthermore, there are plants with larger competitive abilitythey allow the preservation of the soil structure and the good part supporting ecosystem food webs; They are a support for biological diversity.
Examples of perennial plants are lavender, mint, peppermint; also tomatoes or peppers, although in horticulture they are planted and removed annually.
Lavender is a perennial plant whose stem and roots remain alive year after year — Berkan Küçükgül/pixabay
Climate change favors annuals
Ecosystems are maintained in large part thanks to balance between annual and perennial plant populations. Each type fulfills its function, although sometimes disturbances occur that change this balance. And one of the biggest disruptions that all ecosystems on the planet suffer from is anthropogenic climate change.
According to recent research published in Natureclimate change causes a a significant shift in the worldwide distribution of annual and perennial plants. This study shows that changing climate conditions favor annuals over perennials, especially in areas with increased aridity and higher temperatures.
This phenomenon has an evolutionary cause: the high adaptability of annual plants to extreme environments facilitates the colonization of new spaceswhile perennials with longer life cycles and more complex growth needs will find difficulty adapting to how quickly conditions change environment.
Situation in Spain particularly disturbing. Progressive desertification threatens to transform their landscape and favor the most drought-resistant species, but potentially less capable of sustaining the country’s rich biodiversity which, let’s recall, is the largest in Europe.
Although the above-ground part of mint dies each winter, it remains alive underground thanks to underground stems called rhizomes — MW/pixabay
Ecological and biodiversity implications
This imbalance can have serious consequences for ecosystems global, at all levels.
As expected, Annual plants support the biodiversity of ecosystems. Its flowering period, longer in time, allows for maintenance pollinator population during the year; Its higher biomass productivity ensures more food for herbivores; In general, its presence offers stability to food webs. Its decline could destabilize these processes.
On the other hand, perennial plants are essential for them the ability to capture and store carbon for long periods of time. The annual, although it grows very quickly, dies soon and its body decomposes easily, releasing the trapped carbon in a short time. However, the reserve organs of perennial plants function as long-term carbon stores. Replacing them with annual plants with less biomass and shorter life cycles, reduces the ability of ecosystems to retain carbon, which exacerbates climate change. The landscapes may be greener, but they are much poorer and will be of little use.
In nature, there is usually a balance between annuals and perennials, but climate change can change that — kag523/pixabay
Furthermore, replacing perennials with annuals would change the regulation of the water cycle in ecosystems. Perennials with their complex root systems help maintain soil cohesion, facilitating the absorption of water into the subsoil. Its decline would make soils more susceptible to erosion, limiting aquifer recharge and increasing drought and desertification. A particularly serious problem in some vulnerable regions of Spain.
It is imperative to accept conservation strategy and its adaptation to this new scenario in order to mitigate negative impacts on biodiversity and ensure the resilience of ecosystems in the face of emerging environmental challenges. Ongoing research and monitoring will be essential better understand these changes and develop effective responses that protect our natural heritage.
Reference:
- Pereira, SC et al. 2021. Temperature and precipitation extremes in the Iberian Peninsula under climate change scenarios: An overview. Climate, 9(9), 139. DOI: 10.3390/cli9090139
- Poppenwimer, T. et al. 2023. A revision of the global biogeography of annual and perennial plants. Nature, 624(7990), 109-114. DOI: 10.1038/s41586-023-06644-x
